No genome-wide DNA methylation changes found associated with medium-term reduced graphene oxide exposure in human lung epithelial cells

ABSTRACT

The presence of nanomaterials in our everyday life is ever increasing, and so too are concerns about the possible health consequences of exposure to them. While evidence of their biological activity is growing, there is still scant knowledge of the epigenetic mechanisms that could be at play in these processes. Moreover, the great variability in the chemical and physical structures of these compounds handicaps the study of their possible health risks. Here we have synthesized reduced graphene oxide (rGO) through the thermal exfoliation/reduction of graphite oxide, and characterized the resulting material. We have then made use of Illumina’s MethylationEPIC arrays and bisulphite pyrosequencing to analyse the genome-wide and global DNA methylation dynamics associated with the medium-term exposure of human lung epithelial cells to rGO at concentrations of 1 and 10 µg/mL. The results show no genome-wide or global DNA methylation changes associated with either condition. Our observations thus suggest that medium-term rGO exposure does not have significant effects on the DNA methylation patterns of human lung epithelial cells.

KEYWORDS:

• Epigenetics
• DNA methylation
• nanomaterials
• graphene
• exposure

Acknowledgments

Special thanks go to Ronnie Lendrum, the English style editor, for her critical, constructive reading and invaluable comments. We thank Covadonga Huidobro for her help with the BEAS-2B cells.

Availability of data and materials

The raw IDAT and preprocessed data generated in this study by Illumina Infinium MethylationEPIC BeadChip technology are available in the ArrayExpress public repository under accession E-MTAB-7719.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work has been financially supported by: The Plan Nacional de I+D+I co-funding FEDER (PI15/00892 and PI18/01527); the Government of the Principality of Asturias PCTI-Plan de Ciencia, Tecnología e Innovación de Asturias co-funding 2018-2022/FEDER (IDI/2018/146 and IDI/2018/121); AECC (PROYE18061FERN); FGCSIC (0348_CIE_6_E); IUOPA-ISPA-FINBA (The IUOPA is supported by the Obra Social Cajastur-Liberbank, Spain); A.F. Fernández is supported by a Miguel Servet II fellowship (contract CPII16/00007); R.F. Pérez is supported by ISPA-FINBA.